No Time Like the Past - Greg Cox

An original novel set in the universe of Star Trek: The Original Series that reveals long-held secrets about Captain Kirk's past for the first time!

STARDATE 6122.5. A diplomatic mission to the planet Yusub erupts in violence when ruthless Orion raiders attempt to disrupt the crucial negotiations by force. Caught in the midst of a tense and dangerous situation, Captain James T. Kirk of the U.S.S. Enterprise finds an unexpected ally in the form of an enigmatic stranger who calls herself "Annika Seven."

STARDATE 53786.1. Seven of Nine is taking part in an archae­ological expedition on an obscure planetoid in the Delta Quadrant when a disastrous turn of events puts Voyager's away team in jeopardy—and transports Seven across time and space to Yusub, where she comes face-to-face with one of Starfleet's greatest legends.

STARDATE 6122.5. Kirk knows better than most the danger that even a single castaway from the future can pose to the time line, so he and Seven embark on a hazardous quest to return her to her own era. But there are others who crave the knowledge Seven possesses, and they will stop at noth­ing to obtain it—even if this means seizing control of the Enterprise!